Technical data

Basic VHDL simulation
Getting Started with ModelSim PE Tutorial: Using ModelSim PE
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87
This
force
command means:
• Force clk to the value “1” at 50 ns (nanoseconds) after the current time,
• then to “0” 100 ns from now, and
• repeat this cycle every 100 ns.
Step 16.
Select
RUN
on the tool bar. This causes the simulation run for the default simulation length,
which is 100 ns. (The default simulation run length can be modified with
Options >
Simulation Options
from the menu bar.)
Other ways of entering a
run
command include typing it in the Transcript window, or selecting
an option from the Run menu:
Run <default_run_length>, Run Forever, Step, Step Over,
Cont
or
Break
. See "ModelSim menu bar" (p24) for more information about
run
options.
Step 17.
Next type:
run 500
Now that you have run the simulation for 600 nanoseconds, look at the status bar at the bottom
of the Model
Sim
application window. It should look something like this illustration.
Step 18.
If your status bar is different, it is because the status bar changes with the active window. Click
in another Model
Sim
window and examine the status bar again.
Step 19.
Let’s get back to running the simulator.
You can run the simulator for a long time by entering a large number of time units. You can
also make the simulator run to a specific time with a command like this: